Efficiencies of scale killed small business. People had the choice of patronizing small business or large business, and they chose the latter.

Lack of capital investment killed small businesses. Everyone now has to pay a tax penalty to take your earned capital and invest it into local main-street businesses. This capital instead, though 401k, goes into trans-national firms.

I think that the lack of capital investment you're describing can be thought of as a particular instance of the economy of scale (at least, broadly construed): larger and/or conglomerated companies, prima facie, have to depend less on capital injections.

i cannot upvote this enough. The regulation has very little if anything to do with the closure of the vast majority of small businesses. Access to larger/more efficient companies that provide better service to cost has killed the demand for the services that small businesses provide.